1. Field of the Invention
The present invention relates generally to web-roll cartridges, and more particularly to an anti-clock-springing mechanism for preventing a wound roll of web material on a web-spool within a cartridge from clockspringing during storage, handling, and shipment thereof.
2. Description of the Prior Art
In various packages or cartridges now in use for webs of photographic film and paper, the web is wound on a spool or core, with or without flanges, and is disposed within the cartridge which totally surrounds or encloses the web and protects it from light and other damaging effects. One end of the web is normally secured to the core or spool center, and the other end extends out of the cartridge through a slot therein. The other end is fastened to the exterior surface of the cartridge and is released therefrom for insertion into a camera or the like. It has been found that there is a tendency for the web in such cartridges to unwind during storage, handling and shipping. Inasmuch as the inner end of the web is connected to the core or the spool center and the outer end is normally secured to the outer surface of the cartridge, the web acts as a released clockspring, turning the spool as it unwinds. Such clockspringing can result in scratching or abrading the surface of adjacent web convolutions causing a deterioration in the quality of the image that may be recorded thereon. In other instances, the web can clockspring outwardly to the extent that the outer convolution of web jams against the inner surface of the cartridge making subsequent unreeling of the web difficult or impossible. In situations in which the outer end of the web is not fastened to the outer surface of the cartridge, or is inadvertently released from the cartridge surface, the clockspringing can cause the outer end of the web to be pulled back through the slot into the cartridge interior cavity, resulting in a cartridge that is completely unusable.
Various attempts have been made to provide anti-clockspringing apparatus for preventing unwinding of the web in cartridges. For example, an anti-clock-springing device for a film cartridge is disclosed in U.S. Pat. No. 3,613,876, which issued to Kohler et al. on Oct. 19, 1971. In the disclosed film cartridge, one or more spot welds is provided between the surface of the core and the cartridge hub. The spot weld has sufficient strength to prevent the core from rotating during shipping, but will break as the film is withdrawn from the cartridge, permitting the core to rotate. In U.S. Pat. No. 3,784,001, which issued to Bushnell et al. on Jan. 8, 1974, a film cartridge is disclosed in which clockspringing of a roll of film is prevented by providing a frangible connector between the core and a portion of the cartridge. The connector has sufficient strength to prevent the core from rotating during shipping, but which will break as the film is withdrawn from the cartridge, permitting the core to rotate. A core-locking device for a web dispensing cassette is disclosed and published as Item No. 16352 in the November 1977 issue of Research Disclosure. In that core-locking device, a web-winding core is provided with a slotted end, and a core-locking member is provided that is captive and slidable (but yet light-tight) in one of two end caps of the cassette. In U.S. Pat. No. 4,210,296, which issued to Frechette on Jul. 1, 1980, a ribbon cartridge with an integral anti-spool rotation device is disclosed. The anti-spool rotation device comprises an axially movable spool core insert connected to the cartridge wall by flexible bridges or arms. The core insert is manually pressed into the open end of the core to frictionally hold the core against rotation. Upon mounting the cartridge in a machine, a post thereon will axially push the core insert out of frictional engagement with the spool core, thereby allowing free rotation of the web supply spool. It is also known in the prior art to prevent clockspringing of a wound roll of web material within a cartridge by providing aligned notches in outer surfaces of the core end and cartridge wall and placing a rubber band around the entire cartridge with the band nesting in the notches. In still another prior-art reference, U.S. Pat. No. 4,756,418, which issued to Johanson et al. on Jul. 12, 1988, prevention of clockspringing of a wound roll of web material within a cartridge is achieved by providing a notch in a core end alignable with an enclosed slot in a wall of the cartridge, and inserting a clip through the aligned notch and slot. In U.S. Pat. No. 4,802,633, which issued to Beery on Feb. 7, 1989, an anti-clock-springing mechanism is disclosed comprising a ring gear on the flange of the web-spool engageable by a "one-shot" bendable locking gear sector on the cartridge body. The gear sector is normally in engagement with the ring gear to prevent the web-spool from rotating and the web material thereon from clockspringing during shipment and storage of the cartridge. An operating pin is insertable through a light-tight opening in the cartridge for engaging the gear sector and disengaging it from the ring gear to allow web-spool rotation.
Although the aforementioned prior-art attempts at solving the problems of web-roll clockspringing in cartridges have had varying degrees of success, the need still exists for an improved anti-clockspringing mechanism that is of simple design and construction, reliable in operation, and economical to manufacture. An object of the present invention is to fulfill this need.